1. Field of the Invention
This invention relates in general to devices and methods for determination of substances and, more particularly, to methods and devices for assays of binding or bindable substances. Still further, this invention relates to a comparative method and device for a comparative assay of such binding or bindable substances.
2. Description of the Prior Art
In the past, many tests have been provided for determination of binding and bindable substances of various types. Examples of such binding and bindable substances and the substances bound thereto or thereby are antibody-antigens and other binding proteins-protein bindable substances.
An example of a particular type of assay device and method used in the past is described in U.S. Pat. No. 3,654,090 to Schuurs et al. This patent describes a test for determination of either an antigen or an antibody. In one example of the U.S. Pat. No. 3,654,090, a quantity of antigen is attached to an enzyme and a quantity of antibody is insolublized by attachment to insoluble carrier. The enzyme-label antigen and the insolublized antibody are mixed with an unlabelled antigen (the assay substance). By controlling the amount of insolublized antibody and enzyme-labelled antigen, some or all of the enzyme-labelled antigen is not attached to antibody when unlabelled antigen is present. Some or none of the enzyme-labelled antigen is attached. After mixing, the insoluble material is separated from the soluble material which includes any unattached enzyme-labelled antigen. Centrifuging or washing the insoluble material achieves this separation. An enzyme-reactive agent is then added to either the insoluble or soluble portions to assay the enzyme activity. In this manner, the presence of unlabelled antigen (the assay substance) is determined.
Other patents showing similar processes for the determination of binding or bindable substances are shown in U.S. Pat. Nos. 3,791,932 to Schuurs et al; 3,839,153 to Schuurs et al; 3,850,752 to Schuurs et al and 4,016,043 to Schuurs et al. Each of these patents show one component labelled with an enzyme and another made insoluble. As described in U.S. Pat. No. 3,966,897 to Wren et al, the same types of competitive and non-competitive bio-assay processes have been performed by radioactive labelling as opposed to enzyme labelling. Further, as opposed to either radioactive labelling or enzyme labelling, indicator dyes, fluorimetry, spectrofluorotometry or refractomotry can be utilized to measure the assay.
A quantitative assay method and device are described in U.S. Pat. No. 4,425,438 issued Jan. 10, 1984, and assigned to the assignee of the present invention. The quantitative assay device described therein includes a funnel having retained therein glass beads with a competitive binding substance such as a monoclonal antibody affixed thereto. An analytical reagent, such as an enzyme-tagged antigen specific to the monoclonal antibody, is passed over the glass beads such that the reagent is attached and held by the antibodies. Then, if a fluid containing a test substance which competitively binds to the antibodies is passed over the beads, some of the analytical reagent is displaced. The amount of displaced analytical reagent is proportional to the amount of test substance. The amount of analytical reagent is then quantitatively assayed by means of a linear zone of analytic reagent binder. The length of zone colored by an enzyme active coloring agent indicates the quantity of test substance which has been passed over the glass beads in the funnel.
While the above devices have been useful for quantitative and qualitative assays, they are not useful for a comparative assay. Thus, they cannot be utilized to continuously monitor or determine the presence or absence of binding or bindable substances in media such as air or water. Also, the above devices and methods are not satisfactory for completely automated operation. Thus, a technician must operate the equipment and perform the methods for each assay.